In a Long Term Evolution (Long Term Evolution, LTE for short) system version 8, version 9, or version 10, each LTE carrier is backward compatible. Each carrier needs to send a primary synchronization signal (Primary Synchronization Signal, PSS for short), a secondary synchronization signal (Secondary Synchronization Signal, SSS for short), a physical broadcast channel (Physical Broadcast Channel, PBCH for short), a system information block (System Information Block, SIB for short), a physical downlink control channel (Physical Downlink Control Channel, PDCCH for short), cell-specific reference signals (Cell-specific Reference Signal, CRS for short) of all frequency bands and all subframes, and the like that have same resource locations and sending manners as those in the LTE system version 8. Specifically, sending periods of a PSS and an SSS are five subframes. Frequency domain locations of the PSS and the SSS are within a frequency domain width of six physical resource block pairs at a carrier center, and the PSS and the SSS occupy two symbols in a time domain. A PBCH occupies, in a time domain, the first four symbols of a second timeslot in subframe 0, and is also located, in a frequency domain, within a frequency domain width of six physical resource block pairs at a carrier center.
In addition, in LTE version 10, a demodulation reference signal (Demodulation Reference Signal, DMRS for short) is further introduced, and is used by a physical downlink shared channel (Physical Downlink Shared Channel, PDSCH for short) to perform data demodulation. The DMRS is sent only on a physical resource block (Physical Resource Block, PRB for short) that is used to transmit a PDSCH. In LTE version 11, an enhanced physical downlink control channel (Enhanced PDCCH, EPDCCH for short) is further introduced. Frequency division multiplexing is performed between the enhanced physical downlink control channel and a PDSCH, and demodulation is also performed by using a DMRS.
In LTE version 12 or a later version, a new carrier type (New Carrier Type, NCT for short) carrier is introduced. The NCT carrier may be a non-backward compatible carrier, and at least some subframes in the NCT carrier do not have a downlink control region that exists in LTE version 8.
However, because the first four symbols on a backward compatible carrier may be used to transmit a control channel, a DMRS cannot be transmitted in this region. An existing DMRS is sent only on a symbol in a rear part of a subframe in a centralized way. Moreover, in the prior art, a DMRS pattern (DMRS pattern) on a backward compatible carrier is also used on an NCT carrier, that is, on the NCT carrier, a DMRS is sent only on a symbol in a rear part of a subframe in a centralized way, which results in relatively poor downlink transmission performance of the NCT carrier.